The invention relates to a protection helmet specially used by a motor cyclist. The protection helmet is provided with a veil rotatablely fixed at one side of the helmet shell and covered on the opening on the face; the veil is a braking device which can at least apply the brake on the latched position composed of a braking heave, a braking grove on the braking component and a spring which is tightly pressed with each other along the direction of the braking heave and the braking component rotating to the veil. The braking heave and the braking component can be rotatablely arranged along with the veil. The braking groove arranged on the latched position is arranged in a shifting way so that the braking heave can exert a biasing force to the side wall of the braking groove and the veil along the latching direction, which can ensure the veil stably kept at the latched position and suffering an immense wind pressure. |